Electrochemical co-deposition of sol-gel films

ABSTRACT

A method for the co-deposition of sol-gel and one or more additives selected from a great variety of agents including monomers, oligomers, polymers, metals and others is provided. The method affords continuous films of high stability and precision. Also provided is a surface coated with a film of sol-gel and at least one additive electrodeposited according to the presently described methods.

FIELD OF THE INVENTION

This invention relates to a method of electrochemical co-deposition ofsol-gel and different additives to thereby form films on varioussurfaces.

BACKGROUND OF THE INVENTION

Electrochemical deposition, which dates back to the middle of the19^(th) century, is still an extremely powerful process in particularfor depositing metals (electroplating), such as copper, cobalt, nickeland their alloys on various surfaces. Thin metal films, deposited on thesurface of conducting and non-conducting materials by electrolysis playan important role in many fields, such as decorative and anticorrosioncoatings. Electrodeposition of metals, e.g., copper, has become ofutmost significance due to its role in microelectronics.

Electrodeposition of ceramic films employing electrochemical methods isa fast evolving field. The methods for electrodeposition may be dividedinto two: electrophoretic and electrolytic deposition. Electrolyticdeposition can be driven using cathodic currents by either reducing themetal ions, which causes their deposition, e.g., Cu₂O, or by driving aproton-dependent reducing process, leading to an increase of the pH onthe electrode surface and the subsequent metal hydroxide deposition.Alternatively, the deposition of metal oxides and hydroxides can bedriven by anodic currents as a result of oxidizing the metal ions, thusincreasing their oxidation state, which usually results in lowersolubility of their hydroxide salts, such as in Fe(OH)₃ deposition.

Ormocers (ORganically MOdified CERamics) are metal oxides that areformed at room temperature and comprise organic moieties. They areformed as a result of the hydrolysis and condensation of functionalizedtrialkoxymetals, e.g., alkyl-trimethoxysilanes, as shown in Equations 1and 2.

R-M(OR′)₃+3H₂O→R-M(OH)₃+3R′OH  (Eq. 1)

R-M(OH)₃+R-M(OR′)₃→R-M(OH)₂—O-M(OR′)₂+R′OH  (Eq. 2)

There are enormous advantages to using sol-gel technologies forpreparing thin films as the non-hydrolizable group, R, can be used totune the chemical and physical properties of the coating.

Recently, porous solids made of well-ordered silica walls weredeveloped. These porous solids are spatially arranged bymicelle-templating to form channels of regular size in the mesoporousrange. They are called micelle-templated silica, MTS. Their surfacereactivity is rather close to that of silica gel so that graftingorganic functionalities to the inner walls of these silicates withuniform channel structures can be readily achieved. Incorporation oforganic groups in MTS can also be performed by co-condensation undersurfactant control. Due to the fluid character of the sol, the sol-gelsynthesis of ordered mesoporous films on solid substrates is possible,but their use in connection to electrochemistry is scarce.

The electro-assisted deposition of ormocers has recently been reportedby the inventors of the invention disclosed herein (Refs [1]-[3]). Thisapproach takes the advantage of enhancing the hydrolysis andcondensation (both processes are acid and base catalyzed) of the sol-gelprocess by altering the pH at the surface as a result of applying apotential.

The electrodeposition of metal-ceramic composite coatings has beenreported (Refs [4]-[8]) to involve performing the electrolysis in asuspension of ceramic particles. Many various classes of inert particleshave been used; however, best results were obtained with carbides oroxides. On the other hand, the formation of ceramic-metal compositematerials has been accomplished (Refs [9]-[10]) by the incorporation ofmetallic particles in the course of sol-gel formation or the entrapmentof metal cations followed by their reduction. Most of these conventionalmethods are limited by the metals and ceramics that can be deposited anddo not allow precise controlling of the deposit structure. For thesereasons as well as due to the importance of these materials in plating,catalysis, solar cells, etc., there is an enormous interest indeveloping better-controlled and efficient preparation methods formetal-ceramic and ceramic-metal composite materials.

Recently, the inventors of the present invention have developed a methodfor coating a conducting material by electrodeposition of a sol-gel filmof silicon oxide originating from methyltrimethoxysilane (Refs [1] and[11]). The mechanism of the electrochemical sol-gel coating described,involves the alteration of the local pH next to the conducting surface,resulting in an enhancement of the deposition specifically on thedesired surface. This technique was suitable for sol-gel coating of flatsurfaces utilizing a basic pH above 8.2.

LIST OF REFERENCES

-   [1] R. Shacham, et al., Electrodeposition of Methylated-Sol-Gel    Films on Conducting Surfaces. Adv. Mater. 1999, 11, 384-388;-   [2] R. Shacham, et al., Chem. Eur. J., 2004, 10, 1936-1943;-   [3] R. Shacham, et al., J. Sol-Gel Sci. Technol., 2004, 31, 329-334;-   [4] Low, C. T. J., et al., Surface & Coatings Technology 2006, 201,    371-83;-   [5] Kerr, C., et al., Transactions of the Institute of Metal    Finishing 2000, 78, 171-78;-   [6] Benea, L. Materials and Manufacturing Processes 1999, 14,    231-42;-   [7] Helle, K., et al., Transactions of the Institute of Metal    Finishing 1997, 75, 53-58;-   [8] Hovestad, A., et al., Journal of Applied Electrochemistry 1995,    25, 519-27;-   [9] Daniel B. S. S., et al., J. Mater. Proc. Tech., 1997, 68, 132;-   [10] Howe J. M., Inter. Mater. Rev., 1993, 38, 233;-   [11] WO 05/100642.

SUMMARY OF THE INVENTION

The electrochemical co-deposition approach described herein is based onan entirely new concept of electrodeposition of organic sol-gelmaterials by electrochemistry. The two basic processes that lead to theformation of organo-sol-gel materials, i.e., hydrolysis andcondensation, comprise acid/base processes and therefore it is nottrivial that they can be driven by electrochemistry, which, as a personskilled in the art would realize, is mostly used for drivingoxidation/reduction reactions. The invention does not lie only in theapproach, but also in its wide-range potential applications. That is,the process of electrochemical co-deposition of additives andorgano-ceramics as films adds a unique control, i.e., by the appliedpotential, as a means of controlling the film composition as well as thedeposition rate. Since this approach is generic, its applicabilitycovers a wide range of ceramic materials and additives. Possible impactspans from reinforcing metal coatings to forming functionally gradedmaterials.

The uniqueness of the approach disclosed herein lies in the ability toco-deposit an inorganic or organic insulating matrix together with anadditive material, e.g., metallic particles, and conductive polymers andmore so in the ability to form a film on a substrate by controlling thekinetics of both processes which allows tailoring of film morphology.

This co-deposition process affords a film which may in some instanceshave at least two distinct phases.

Additionally, the inventors have shown that such an electrochemicalco-deposition method of sol-gel and at least one additional additive isreproducible and highly versatile. Some additional advantages ofemploying the method of the invention as compared with other knownmethods for coating surfaces are:

1. Since electron transfer occurs very close to the surface, i.e.,within less than 100 Å, the coating follows very closely the intimatestructure of the surface, allowing the coating of complex geometries,such as screws, stents, sprints, etc;

2. The thickness of the coating and the nature thereof is highlycontrollable and depends primarily on the ratio between the sol-gelmonomer and the additional substance and the potential applied andduration of application;

3. The method may be used with reproducible results, affording coatingsof a great variety, on a great variety of surfaces, including those withcomplex geometries;

4. A great variety of additives may be used;

5. The inclusion of the additive in the reaction mixture does notinterfere with the sol-gel polymerization; and

6. The electrochemical sol-gel polymerization process allows forsecondary processes such as reductions of metal or organic compounds totake place at the same time without affecting or interfering with thesol-gel polymerization process.

Accordingly, in one aspect of the present invention, there is provided amethod for electrochemical co-depositing on a conductive surface a filmof sol-gel and at least one additive, said method comprising inducing anelectrochemical reaction on said conductive surface in the presence of acomposite of at least one sol-gel precursor and at least one additive,thereby obtaining a film of said composite on the surface.

In some embodiments, the at least one additive is selected so as to becapable of undergoing reduction or oxidation during theelectrodeposition process.

The composite as used in the context of the present invention is acombination of at least one sol-gel precursor and at least one additive,each having different properties than that of the composite as a whole,and have different chemical and physical characteristics such that theydo not dissolve or merge completely in one another. Complete dissolutionof both in a liquid medium (e.g., a solution) is nevertheless requiredfor the formation of the composite. In the composite, the sol-gelprecursors and the additives have strong interactions therebetween, suchinteractions being one or more of covalent, electrostatic,complex-forming interactions, hydrophobic-hydrophilic and hydrogenbonding. In the absence of such strong interactions, only doping isachieved, namely, only minute quantities of the at least one additive,as defined herein, will be deposited along with the sol-gel.

The composite is typically prepared as a solution of at least onesol-gel precursor and at least one additive. The solution may beprepared by adding the components simultaneously and mixing untilcomplete dissolution of both components is achieved or by adding onecomponent after the other as demonstrated herein below. In oneembodiment, said solution is an aqueous solution. In another embodiment,the solution is an alcoholic solution containing water. In anotherembodiment, the composite is a nanocomposite.

As stated above, the method allows the electro co-deposition of sol-geland an additive(s). It should be noted that herein, for the sake ofclarity, the term “electro co-deposition” is used interchangeably withthe “electrodeposition of the composite”, as defined. The term“co-deposition” or any lingual variation thereof, refers to the“depositing together”, namely to a single-step simultaneous depositionof the two components, namely sol-gel and additive(s) and the formationof a film or a coat on a substrate according to the invention, whereinthe film which is formed is a hybrid (in some cases two-phase) film ofthe sol-gel and additive (the phases can be of the order of a fewnanometers resulting in nanocomposite materials). In some embodiments,in the process of co-deposition, a sol-gel polymerization reaction takesplace simultaneously with the reduction of a metal or an oxidation of anorganic compound, such as pyrrole.

The sol-gel precursors are typically monomers, which can undergopolymerization under the electrochemical conditions employed. Theprecursors are selected from metal alkoxide monomers, transition metalalkoxide monomers, silicon alkoxide monomers, metal ester monomers,transition metal ester monomers, silicon ester monomers, monomers of theformula (RO)_(n)M(R′)_(4-n), partially hydrolyzed and/or partiallycondensed polymers of said monomers and mixtures thereof, wherein in theformula (RO)_(n)M(R′)_(4-n), M is selected from a silicon atom, ametallic or semimetallic element such as Si, Zr, Ti and others, R is anorganic moiety selected from C₁-C₃-alkyl, being preferablyunsubstituted, R′ is an organic moiety selected from C₁-C₁₀-alkyl,C₂-C₈-alkenyl, C₂-C_(g)-alkynyl, C₆-C₁₀-aryl, C₄-C₁₀-heteroaryl, eachbeing optionally substituted by at least one group selected fromC₁-C₈-alkyl, C₂-C₈-alkenyl, C₂-C₈-alkynyl, C₆-C₁₀-aryl,C₄-C₁₀-heteroaryl, halide, amine (primary, secondary, tertiary orquaternary), hydroxyl, thiol, nitro, repeating methylenedioxy(—O—CH₂—O—) or ethylenedioxy (—O—(CH₂)₂—O—) groups, and n is an integerfrom 1 to 4.

In one embodiment, the at least one sol-gel precursor is a mixture ofsuch precursors. In another embodiment, the mixture of precursors ischosen so as to improve one or more of the following properties of thecoating: adhesion, charge and charge distribution, hydrophobicity,hydrophilicity, thickness, reactivity, resistivity, resistance tooxidation, etc.

In another embodiment, the precursors are monomers being selectedamongst metal alkoxide monomers and silicon alkoxide monomers.

In still another embodiment, the silicon alkoxide monomer is of theformula (RO)_(n)Si(R′)_(4-n), wherein R is an organic moiety selectedfrom C₁-C₃-alkyl, R′ is an organic moiety selected from C₁-C₁₀-alkyl orC₆-C₁₂-aryl, optionally substituted by at least one amine or thiolgroup, and n is an integer from 1 to 4, or partially hydrolyzed andpartially condensed polymer thereof, or a mixture thereof.

Within the context of the present invention, the term “alkyl” refers toan aliphatic moiety having at least 1 carbon atom and being optionallysubstituted by at least one group selected from C₂-C₈-alkenyl,C₂-C₈-alkynyl, C₆-C₁₀-aryl and C₄-C₁₀-heteroaryl, optionally substitutedby at least one group selected from C₁-C_(g)-alkyl, C₂-C₈-alkenyl,C₂-C₈-alkynyl, C₆-C₁₀-aryl, C₄-C₁₀-heteroaryl, halide, amine (primary,secondary, tertiary or quaternary), hydroxyl, thiol, nitro and repeatingmethylenedioxy (—O—CH₂—O—) or ethylenedioxy (—O—(CH₂)₂—O—) groups. Forexample, the specific designation “C₁-C₃-alkyl” refer to an alkyl grouphaving between 1 and 3 carbon atoms and unless specifically defined maybe substituted. Unless specifically stated, the alkyl group may belinear or branched. Non-limiting examples of alkyl groups are a methyl,ethyl, propyl, isopropyl, butyl, 2-butyl, pentyl, hexyl, heptyl, octyl,nonyl and dodecyl.

The term “alkenyl” refers to a carbon chain having at least 2 carbonatoms and at least one double bond, which may be at one of the terminalpositions of the chain or be an inner-chain double bond. The term“alkynyl” refers similarly to a carbon chain having at least two carbonatoms and at least one triple bond which may be a terminus bond or aninner-chain triple bond.

The term “aryl” refers to an aromatic moiety, preferably a benzene ring(i.e., a phenyl ring), which may optionally be substituted by at leastone or more functional group, provided that such does not interfere withthe hydrolysis and condensation of the sol-gel, said group beingselected from C₁-C₈-alkyl, C₂-C₈-alkenyl, C₂-C₈-alkynyl, C₆-C₁₀-aryl,C₄-C₁₀-heteroaryl, halide, amine (primary, secondary, tertiary orquaternary), hydroxyl, thiol, nitro and repeating methylenedioxy(—O—CH₂—O—) or ethylenedioxy (—O—(CH₂)₂—O—) groups. The aryl group mayalso be a biaryl such as a biphenyl. The specific designation“C₆-C₁₂-aryl” refers to an aromatic moiety having between 6 carbon atomsand 12 carbon atoms. Non-limiting examples of aryls are a phenyl,biphenyl, and naphthyl.

Within the scope of the present invention, the term “aryl” alsoencompasses heteroaryls having between 5 and 10 atoms, at least one ofwhich being a heteroatom selected from N, O and S. The heteroaryls maybe similarly substituted.

In another embodiment, M is a metal atom or a transition metal atomselected from Si, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu(I) Zn, Y, Zr,Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, La, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hgand Ac and mixtures thereof.

In a further embodiment, said metal is Si, Zr, Al, Ti, Fe, V, and W.

In some embodiments, the sol-gel precursor is a metal oxide selectedfrom (i) aluminum oxides such as, but not limiting to, aluminumtriethoxide, aluminum isopropoxide, aluminum sec-butoxide, and aluminumtri-t-butoxide; (ii) titanium oxides such as, but not limiting to,titanium methoxide, titanium ethoxide, titanium isopropoxide, titaniumpropoxide, titanium butoxide, titanium ethylhexoxide, titanium(triethanolaminato)isopropoxide, titanium bis(ethylacetoacetato)diisopropoxide, and titaniumbis(2,4-pentanedionate)diisopropoxide; (iii) zirconium oxides such as,but not limiting to, zirconium ethoxide, zirconium isopropoxide,zirconium propoxide, zirconium sec-butoxide, and zirconium t-butoxide;(iv) aluminum oxides such as, but not limiting to, and aluminumdi-s-butoxide ethylacetonate; (v) copper (I) oxides such as, but notlimiting to, copper ethoxide, and copper methoxyethoxyethoxide; (vi)titanium oxides such as, but not limiting to, titanium dioxide andtitanium n-nonyloxide; (vii) vanadium oxides such as, but not limitingto, vanadium tri-n-propoxide oxide, and vanadium triisobutoxide oxide;(viii) silicon oxides such as silicon dioxide; and combinations of twoor more of the above compounds.

Metal salts such as metal carboxylates, metal halides, and metalnitrates may also be added as the metal oxide compound to make thesol-gel precursors. Metal carboxylates include metal acetates, metalethylhexanoates, metal gluconates, metal oxalates, metal propionates,metal pantothenates, metal cyclohexanebutyrates, metal bis(ammoniumlacto)dihydroxides, metal citrates, and metal methacrylates. The metalsare the same metals as the metal alkoxides. Specific examples of metalcarboxylates include aluminum lactate, acetate, ethylhexanoate,gluconate, oxalate, propionate, pantothenate, cyclohexanebutyrate, andmethoxyethoxide, iron alkoxide, iron isopropoxide, tin acetate, tinoxalate, titanium bis(ammonium lacto)dihydroxide, zinc acetate, zincmethacrylate, zinc stearate, zinc cyclohexanebutyrate, zirconiumacetate, and zirconium citrate.

In some cases, the at least one sol-gel precursor is an organosilanesuch as phenyltrimethoxysilane; phenyltriethoxysilane;diphenyldimethoxysilane; diphenyl diethoxysilane;3-aminopropyltrimethoxysilane; 3-aminopropyltriethoxysilane;N-(3-trimethoxysilylpropyl)pyrrole;N[3-(triethoxysily)propyl]-4,5-dihydroimidazole;beta-trimethoxysilylethyl-2-pyridine;N-phenylaminopropyltrimethoxysilane; 3-(N-styrylmethyl-2-aminoethylamino)propyltrimethoxysilane;methacryloxy-propenyltrimethoxy silane;3-methacryloxypropyltrimethoxysilane; 3-methacryloxypropyltris(methoxyethoxy)silane; 3-cyclopentadienylpropyltriethoxysilane;7-oct-1-enyl trimethoxysilane, 3-glycidoxypropyl-trimethoxysilane;gamma-glycidoxypropyl methyldimethoxysilane;gamma-glycidoxypropylpylpentamethyldisiloxane;gamma-glycidoxypropylmethyldiethoxysilane;gamma-glycidoxypropyldimethylethoxysilane;(gamma-glycidoxypropyl)-bis-(trimethylsiloxy)methylsilane;vinylmethyldiethoxy silane; vinylmethyldimethoxysilane;methylaminopropyltrimethoxysilane; n-octyl triethoxysilane;n-octyltrimethoxysilane; hexyltriethoxysilane; isobutyltrimethoxysilane; 3-ureidopropyltriethoxysilane;3-isocyanatepropyltriethoxysilane;N-phenyl-3-aminopropyltrimethoxysilane;3-triethoxysilyl-N-(1,3-dimethyl-butyliden) propylamine;N-2(aminoethyl)-3-aminopropyltriethoxysilane; triethoxysilane;N-2(aminoethyl)-3-aminopropyltrimethoxysilane;N-2(aminoethyl)-3-aminopropylmethyldimethoxysilane;3-acryloxypropyltrimethoxysilane;methacryloxypropylmethyldiethoxysilane;meth-acryloxypropylmethyldimethoxysilane;glycidoxypropylmethyldiethoxysilane;2-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane; vinyltriethoxysilane;amonophenyl trimethoxysilane; p-chloromethyl)phenyltri-n-propoxysilane;diphenylsilanediol; vinyltrimethoxysilane;2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; epoxyhexyltriethoxysilane; tris(3-trimethoxysilylpropyl)isocyanurate; dococentyltrimethoxysilane; 3-mercaptopropyltriethoxysilane;1,4-bis(trimethoxysilylethyl)benzene; phenylsilane;trimethoxysilyl-1,3-dithiane;n-trimethoxysilylpropylcarbamoylcaprolactam;2-(diphenylphosphine)ethyltriethoxysilane,3-cyanopropyltrimethoxysilane, and diethylphosphatoethyltriethoxysilane.

In some embodiments, the sol-gel precursor is one or more of TiO₂, SiO₂,titanium tetra-n-propoxide (Ti(OPr)₄), phenyltrimethoxy silane (PhTMOS),aminopropyltriethoxy silane (APTEOS), tetramethoxysilane (TMOS),tetraethoxysilane (TEOS), and silicon oxide.

The at least one additive of the composite may be any substance which isinert to the sol-gel process, does not interfere therewith, does nottake part in the sol-gel polymerization (namely, it is not an essentialcomponent of the sol-gel polymerization process which can proceed evenin its absence) and which is distributed in the sol-gel film in ahomogenous or heterogeneous fashion.

The at least one additive may be a mixture of different additives, indifferent quantities or in different forms. Non-limiting examples of theat least one additive are reinforcing elements, metals, metal salts,fillers, polymers, monomers, nanoparticles, encapsulated materials, andcomposite matrix binders.

In one embodiment, the at least one additive is a mixture of additives,such as two or more different polymers or two or more different monomersthereof.

In another embodiment, the at least one additive is a plurality ofmicro- or nanoparticles or nano- or microcapsules constructed fromand/or containing different materials.

In a further embodiment, the at least one additive is a substance whichis capable of undergoing a reduction or an oxidation under theconditions employed, without interfering with the sol-gel deposition.Non-limiting examples of such are monomers, oligomers, metals, and metalsalts.

In a still further embodiment, the at least one additive is an additiveor a plurality thereof, such as monomers or oligomers, capable ofpolymerizing during the electrochemical co-deposition process withoutaffecting the sol-gel process.

Typically, the ratio between the sol-gel and the additive may range from1:1, 10:1, 100:1, 100:1, 1000:1, respectively, or any ratiotherebetween. As such, a person skilled in the art should realize thatthe at least one additive is not a doping agent or a dopant existing inthe film in minute concentrations (ppm or lower) so as to alter aspecific property or a colloquium of properties of the substance inwhich it is present. In contrast to dopants added in so-called “dopingquantities”, the at least one additive of the composite constitutes asubstantial part of the composite, as demonstrated in the examplesbelow.

In one embodiment, the at least one additive is at least one monomer ofa conducting polymer which polymerizes independently of thepolymerization of the sol-gel, without disrupting it, and the methodaffords a surface coated with a film of sol-gel embedded with aconductive polymer.

In another embodiment, the at least one additive is a polymer. In stillanother embodiment, said polymer is conductive.

In another embodiment, the at least one additive is a prepolymer, i.e.,an oligomer made of several monomers capable of further polymerization.

The conductive polymers or monomers thereof which are suitable for usein the present invention include, in a non-limiting fashion, polymershaving a polymeric component of one or more olefin, such aspolyethylene; polyacetylenes, polypyyroles, polythiophenes, andpolyanilines, copolymers thereof and blends of two or more suchpolymers. Each of said conductive polymer may or may not be substituted.

The polypyrroles may be selected from, in a non-limiting fashion,unsubstituted polypyrrole, alkylated polypyrrole, copolymers ofpolypyrrole, polypyrrole/poly (styrene sulfonic acid), 3,4-dialkoxysubstituted polypyrrole styrene sulfonate, and 3,4-dialkoxy substitutedpolythiophene styrene sulfonate.

As stated above, the at least one additive may be the polymer it self ora precursor thereof in the form of monomers, oligomers or shorterpolymers capable of undergoing polymerization into the desired polymer.

In another embodiment, the polymer is pluronic, preferably F127,polyethylene glycol of various molecular weights, and oligo orpolypyrrole or other conducting polymers of various molecular weights.

In yet another embodiment, the at least one additive is a plurality ofnanoparticles. In some embodiments, the nanoparticles contain at leastone substance or mixture of substances. In other embodiments, thenanoparticles are hollow (empty, or contain a gas or a non-particularsolvent).

The nanoparticles which may be added as additives may be made of avariety of materials such as silica, carbon, metals of different types,such as gold, platinum or metal oxides thereof. In some embodiments, thenanoparticles are silica hollow particles. In other embodiments, thenanoparticles are particles encapsulating at least one substance or amixture of substances.

The substance or mixture of substances which may be encapsulated in theparticles may be selected from drugs, fillers, metals, metal oxides,metal salts, metal particulates, reinforcing materials, colorants,fluorescent materials, magnetic materials, and semiconductive materials.

In another embodiment, the at least one additive is a metal. In someembodiments, the metal is added to the reaction solution in the form ofa metal salt. Non-limiting examples of such metals are copper (II),cobalt, nickel, silver, palladium and gold.

The at least one metal salt may be added as a solid (as powder orsemi-solid) to the solution containing the sol-gel precursors andthereafter allow to dissolve therein, as a concentrate (a highconcentration solution of the metal salt), or as a solution of any otherconcentration. The solution may be a water solution containing only themetal salt and water, or an aqueous solution containing also inert metalforms (being different from the additive metal salts), alcohol, acids,bases or other additives.

In one embodiment, the at least one metal salt is one metal salt.

In other embodiments, the at least one metal salt is a mixture of saltsof the same metal but of at least two different counter ions.

In further embodiments, the at least one metal salt is a mixture ofsalts of different metals.

The at least one metal salt is not a dopant.

As stated above, in order for the electrodeposition of the composite tosucceed, the surface to be coated (be it the whole surface or a portionthereof which coating is desired) must be conductive. In cases where thesurface is conductive only in specific regions thereof, theelectrodeposition will be affected at the conductive regions only.Surfaces which are non-conductive may be coated with a conductive layer,for example by electroless processes, before sol-gel electrodeposition.As a person skilled in the art would recognize, the term “conductive”refers generally to the ability of the surface to conduct electriccurrent. The conductivity of surfaces may be measured according tomethods known in the art.

The conductive surface to be coated according to the invention may be asurface of any device, structure, article, or element. The surface maybe flat, smooth, coarse, round, a three-dimensional surface, innerand/or outer surfaces, a surface having regions of restricted access andcavities, multilayered surfaces and a surface of any thickness,constitution and size.

The conductive surfaces may be for example of metallic materials oralloys such as, but not limited to, stainless steel (316L), MP35N (analloy of 35% cobalt, 35% nickel, 20% chromium, and 10% molybdenum),MP20N (an alloy of 50% cobalt, 20% nickel, 20% chromium, and 10%molybdenum), ELASTINITE (Nitinol), cobalt-chromium alloys (e.g.,ELGILOY), tantalum, tantalum-based alloys, nickel-titanium alloy,platinum, platinum-based alloys such as platinum-iridium alloy, iridium,gold, magnesium, titanium, titanium-based alloys, zirconium-basedalloys, copper, graphite, or combinations thereof. Semiconductive orsuperconductive compounds may also serve as conductive surfaces suitablefor the electrodeposition of the invention. Devices made frombioabsorbable or biostable polymers can also be used with theembodiments of the present invention, provided that at least a portionthereof to be coated is conductive.

In one embodiment, said surface is made of stainless steel. In apreferred embodiment, the stainless steel is stainless steel 316L.

In another embodiment, said surface is a metallic surface.

In yet another embodiment, said surface is made of indium-tin oxide(ITO).

Non-limiting examples of devices, structures, articles, and elementshaving such surfaces are metals wires, metal sheets, metallic surfacesof electronic devices, patterned surfaces, electric elements, medicaldevices, medical implants, household appliances, refractive elements,structures requiring insulation, and containers.

In one embodiment, said surface is the surface of a medical device or animplant. As a person skilled in the art would recognize, a medicalimplant is a structure which may be implanted into the body of ananimal, e.g., non-human or human. The structure may be implanted in thebody of the subject during a medical procedure which purpose may be thetreatment or prevention of a disease or disorder or the diagnosis of acondition. The implant may also be one which is used as a vehicle forproviding therapy. The implant may act as scaffoldings, functioning tophysically hold open and, if desired, to expand the wall of apassageway, inserted through small vessels, such as via catheters, andthen expanded to a larger diameter once it is at the desired location.Non-limiting examples of such medical implants are a stent, anartificial heart valve, a cerebrospinal fluid shunt, a pacemakerelectrode, an axius coronary shunt, an endocardial lead, an orthopedicdevice, and a vessel occlusion device.

In one embodiment, the surface to be coated by the composite accordingto the invention is the surface of a medical implant, said compositecomprising apart from the sol-gel precursors a plurality ofnanoparticles containing at least one drug. The at least one drug may beselected, in a non-limiting fashion amongst analgesics/antipyretics,antiasthamatics, antibiotics, antidepressants, antidiabetics, antifungalagents, antihypertensive agents, anti-inflammatories, antineoplastics,antianxiety agents, immunosuppressive agents, antimigraine agents,sedatives/hypnotics, antipsychotic agents, antimanic agents,antiarrhythmics, antiarthritic agents, antigout agents, anticoagulants,thrombolytic agents, antifibrinolytic agents, antiplatelet agents andantibacterial agents, antiviral agents, antimicrobials, anti-infectives,and combination thereof.

In another embodiment, said medical implant is a stent or an orthopedicdevice such as a screw or nail.

As stated hereinbefore, the coating of the conductive surface by a filmof the composite is achieved by the induction of electrochemicalreaction on the surface to be coated. The induction of theelectrochemical reaction is typically achieved by applying a voltage tosaid surface while in contact with the composite. In a typicalexperiment, DC power supply has the negative output lead electricallyconnected to the surface to be coated through one or more contacts. Thepositive output lead of the power supply is electrically connected to ananode located in the plating solution comprising the additives, sol-gelprecursors and other agents as detailed before. Duringelectrodeposition, power supply biases the surface to provide a negativepotential relative to the anode causing electrical current to flow fromthe anode to the surface. This causes an electrochemical reaction on thesurface to be coated which results in deposition of the composite of asol-gel and an additive on the surface.

The term “contacting” or any lingual variation thereof, refers withinthe context of the present invention to having the surface and thecomposite in intimate proximity to allow the above detailedelectro-co-deposition, i.e., the formation of a film on the surface.Preferably, the contacting is achieved by immersion of the surface in acomposite solution containing the sol-gel precursors and the at leastone additive, as disclosed.

Thus, in another embodiment, the method comprises:

-   -   (i) providing a conductive surface, as defined;    -   (ii) providing a composite of at least one sol-gel precursor and        at least one additive, said composite being in a solution;    -   (iii) contacting said surface with a solution comprising the        composite;    -   (iv) applying a voltage to said surface in contact with the        composite, thereby inducing formation of a sol-gel film on the        surface.

Preferably, the at least one additive is selected so as to have thecapability of undergoing reduction or oxidation during theelectrodeposition process.

In one embodiment, the contacting is achieved by immersion of thesurface in a solution containing the composite prior to and throughoutthe electrodeposition process.

The term “solution” refers to the liquid media in which the sol-gelprecursors and at least one additive are contained. In some embodiments,the solution further contains at least one electrolyte that can reducethe solution resistance. In some other embodiments, the solution is atransparent solution. In other embodiments, the solution is an emulsion.In other embodiments, the solution is a microemulsion. In furtherembodiments, the solution comprises micelles.

The solution may a pre-made solution of all required components or maybe a solution which is assembled by adding each of the components at adifferent point in the process. However, as the solution has to containa mixture of the sol-gel precursors and additives, the addition of eachshould take place sufficient time prior to contacting with the substrateso as to allow formation of the composite.

The applied voltage is typically a low voltage which application createsa positive or negative potential for a determined period of time. Thepotential is selected to allow the deposition of the composite on thesurface.

In one embodiment, the potential is selected to allow sol-gelpolymerization reaction and reduction or oxidation of at least oneadditive on the surface. A person skilled in the art would be able toascertain from available data or previous experiments the potential orpotential range which would be necessary to achieve both the primarysol-gel polymerization and the secondary reduction/oxidation of e.g.,the metal or the organic monomer or oligomer. For data concerningreduction/oxidation potentials of a great variety of organic andinorganic materials, one may refer to “CRC Handbook of Chemistry andPhysics”, David R. Lide, Ed, 86^(th) Edition, 2005.

Generally, the applied voltage is a low voltage not exceeding a fewvolts in its absolute value.

In one embodiment, said voltage not exceeding a few volts in itsabsolute value is a voltage between (−1.7) V to (+2.6) V versus Ag/AgBr.In another embodiment, the voltage is between (−1.4) V to (+1.4) V. Inanother embodiment, the voltage is between (−1.0) V to (+1.4) V.

In another embodiment, the metal to be reduced and co-deposited iscopper and the potential is between ±1.0 V and ±1.4 V.

In another embodiment, the sol-gel to be deposited along with a metalsalt is SiO₂ or TiO₂ and the potential is between ±1.0 V and ±1.4 V.

In a further embodiment, the additive is polypyrrole (PPY) and thevoltage is between 0.7 V and 1V.

In still another embodiment, the additive is pyrrole (monomers) and thevoltage required for its polymerization and electrochemicalco-deposition is between 0.5 V and 1V.

In a still further embodiment, the voltage is applied for a period offrom about 5 minutes to about 60 minutes.

In another embodiment, said negative or positive potential induceselectrochemical formation of solvated H⁺ or OH⁻.

In yet another embodiment, said solution comprising the sol-gelprecursors further comprises at least one alcohol, water and at leastone inert salt. The alcohol is a C₁-C₄-alcohol selected from methanol,ethanol, propanol, iso-propanol, 1- or 2-butanol, tert-butanol and2-methylpropanol. The at least one inert salt, being different from saidat least one metal salt, is a water-soluble salt which can dissociatesinto ions to reduce the solution resistance. In some embodiments, the atleast one inert salt is a salt of an alkali metal such as Na, K, and Li.In other embodiments, the at least one inert salt is a tetralkylammoniumsalt.

Non-limiting examples of such inert salts are NaCl, NaBr, KCl, KBr,LiClO₄, KNO₃, KBF₄ and ammonium NH₄ ⁺ containing salt.

In another embodiment, the method comprises:

-   -   (i) providing a conductive surface;    -   (ii) providing a composite of at least one sol-gel precursor and        at least one additive, said composite being in a solution;    -   (iii) immersing said surface in a solution comprising a        composite according to the invention, at least one alcohol,        water and at least one inert salt;    -   (iv) applying a voltage to said conductive surface being        immersed in said solution comprising the composite,        thereby inducing formation of a sol-gel film on said surface.

In another embodiment, said at least one additive is a monomer of aconductive polymer and the method comprises:

-   -   (i) providing a conductive surface;    -   (ii) providing a composite of at least one sol-gel precursor and        a plurality of monomers of at least one conductive polymer, said        composite being in a solution;    -   (iii) immersing said surface in a solution comprising a        composite according to the invention, at least one alcohol,        water and at least one inert salt;    -   (iv) applying a voltage to said conductive surface being        immersed in said solution comprising the composite,        thereby inducing the polymerization of sol-gel and oxidation of        said plurality of monomers of at least one conductive polymer,        whereby a hybrid sol-gel/conductive polymer film is deposited on        said surface.

In another embodiment, the at least one additive is a metal and themethod comprises:

-   -   (i) providing a conductive surface;    -   (ii) immersing said surface in a solution comprising sol-gel        precursors, at least one alcohol, water and at least one inert        salt;    -   (iii) inducing an electrochemical reaction on said conductive        surface by applying voltage to said surface being immersed said        solution; and    -   (iv) treating said solution with at least one metal salt;        thereby inducing the polymerization of said sol-gel and        reduction of said metal salt, whereby a hybrid sol-gel/metal        film is deposited on said surface.

In some embodiments, the step of treating the solution with said atleast one metal salt is carried out before induction of theelectrochemical reaction.

In some other embodiments, the solution of step (ii) is admixed with atleast one metal salt prior to the immersion of the surface therein.

In another aspect of the present invention, there is provided a surfacecoated with a film of a composite of at least one sol-gel precursor andat least one additive, deposited as defined above, said film being ahybrid film.

In yet another aspect of the present invention there is provided asurface coated with a hybrid film according to the methods of theinvention.

The film produced according to the methods of the invention is referredto as a hybrid film. The homogeneity or heterogeneity of the two-phasefilm, namely the visual appearance of micro- or nanostructures in thesol-gel matrix may be determined visually by the naked eye, under anoptical or electronic microscopes. Without wishing to be bound bytheory, the presence of such micro- or nanostructures in the filmdepends on the grain size of the embedded additive material(s), whichmay be in the micrometer scale and/or in the nanometer scale. Typically,a film is said of being a hybrid homogenous film when a single phase isobserved by the naked eye or under an optical or electronic microscope,under the specific resolution. In some cases, a homogenous film may beobserved even at a high resolution. In such cases, the film may be aclassic continuous and homogenous film or may have small enoughnanostructures which are not observed even under the high resolutionemployed.

The films prepared according to the invention may have differentthicknesses based on the reaction time and/or voltage employed.Typically, the electrodeposited two-phase film is between about 1 and100 micrometer thick.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the invention and to see how it may be carriedout in practice, embodiments will now be described, by way ofnon-limiting example only, with reference to the accompanying drawings,in which:

FIGS. 1A-C show scanning electron microscope (SEM) images of Cu/TiO₂—electrodeposited films (−1.4V), deposited on ITO at three differentconcentrations: FIG. 1A 100 mM, FIG. 1B 10 mM. and FIG. 1C, inaccordance with the method of the invention.

FIGS. 2A-B show SEM images of electrodeposited Cu/TiO₂ upon applying aless negative potential of ±1.0 V (FIG. 2A) and electrodeposited Cu/SiO₂upon applying a potential of ±1.4 V (FIG. 2B).

FIGS. 3A-B show electrochemically co-deposited Cu/TiO₂ that was peeledoff the surface (FIG. 3A) and a cross-section of a layer deposited onITO (FIG. 3B).

FIGS. 4A and 4B show scanning electron micrograph (SEM) images of a filmof PEG 20000 co-deposited with phenylTMOS (deposition ratio 1:1) onstainless steel plate, according to the invention (FIG. 4A). An image ofa bare stainless plate is shown in FIG. 4B.

FIGS. 5A and 5B show SEM images of two two-phase films of F127co-deposited with APTEOS (deposition ratio 0.1:1) on stainless steelplate.

FIGS. 6A and 6B show SEM images of a film of pure PhTMOS (FIG. 6A) andof a composite of PhTMOS and pluronic (FIG. 6B).

FIGS. 7A and 7B are scanning electron micrographs (SEM) of a stentelectrochemically coated with a mixture of sol-gel and pluronic.

FIGS. 8A and 8B are electrochemically deposited films made of silicananoparticles containing a fluorescent dye and tetramethoxysilane.Picture A was acquired by SEM. Picture B was taken by a fluorescenceoptical microscopy.

FIGS. 9A-9D show SEM images of PPY/SiO₂ electrodeposited films afterapplying different positive potential: FIG. 9A at 0.7 V, FIG. 9B at 0.8V, FIG. 9C at 0.9 V, and FIG. 9D at 1V.

FIGS. 10A and 10B depict in FIG. 10A the optical micrograph of fourdifferent electrochemically deposited sol-gel/pyrrole samples, whichwere deposited under different potentials, as shown. In FIG. 10B isdepicted a SEM image of an electrochemically depositedsol-gel/polypyrrole film.

FIGS. 11A-11D show EDX analysis plots of the film shown in FIGS. 6A-6D,at different potentials: FIG. 11A at 0.7 V, FIG. 11B at 0.8 V, FIG. 11Cat 0.9 V, and FIG. 11D at 1V.

FIG. 12 shows the absorbance measurements of the electrodeposited films,PPY/SiO₂.

FIG. 13 shows electrodeposited films obtained at different depositiontimes.

FIGS. 14A-14B show SEM images of PPY and PhTMOS electrodeposited film attwo different resolutions: 2500× (FIG. 14A) and 10,000× (FIG. 14B).

DETAILED DESCRIPTION OF EMBODIMENTS

Sol-gel polymers are usually formed as thin films or coatings with athickness that can vary between a few nanometers to tens of microns. Themost common methods for depositing sol-gel films are dip-coating,spin-coating and spraying.

The inventors of the present invention have now surprisingly found thatcomposite materials comprising additives such as metals, polymers andparticulates may be embedded in a sol-gel film electrodeposited on asurface. Despite what had been suspected at the onset of experimentationthat electrodeposition of a foreign, non-sol-gel precursor material mayresult in a disruptive interaction with the sol-gel precursors and theproduction of a defective sol-gel layer, it has now been shown that theadditives recited herein may be embedded in a sol-gel layer providedthat the sol-gel precursors and at least one additive are presented as acomposite material as defined hereinabove.

When the additive is added not as part of a composite, and therefore inthe absence of a strong interaction with the sol-gel precursors, theamount of incorporated additive is reduced to nil. It should be pointedout that thus far deposition of sol-gel together with additionalmaterials was succeeded only by using conventional dip-coating,spin-coating or spraying methods.

Without being limited by theory, it is presumed that the electrochemicaldeposition of the present invention may be driven by the formation of anetwork that embeds the other substance, e.g., polymer or metal, andforces it to deposit in the course of sol-gel deposition.

The single step electrochemical method for the preparation ofsol-gel-additive, e.g., copper-sol-gel or PPY-sol-gel films involves theapplication of either negative or positive potentials to a conductingsubstrate which alters the pH at the electrode surface, and catalysesthe polymerisation of sol-gel monomers, leading to the deposition of theappropriate oxide films. This method of the invention has beensuccessfully employed for the coating or codeposition of such metals ascopper and titania as well as copper and silica to form Cu/TiO₂ andCu/SiO₂ films, respectively, and also for the deposition of conductivepolymers and monomers thereof on such surfaces.

Example 1 Electrodeposition of a Composite Containing Copper Metal andSol-Gel

A standard three-electrode cell was used. A potential of −1.4 V vs.Ag/AgBr was applied to an electrode such as indium-tin oxide (ITO, R≦10Ohm/Ω, Delta Technologies) for 0.5-60 min, while stirring the depositionsolution (0.2 M titanium tetra-n-propoxide (Ti(OPr)₄), 8.9 mM water and0.1 M LiClO₄ in dry 2-propanol). CuCl₂ was dissolved in this solution(1-100 mM). The ITO samples were pulled out of the deposition solution(maintaining the stirring and the potential) at a rate of 50

FIGS. 1A-C are SEM images of Cu/TiO₂ films deposited at three differentconcentrations (100, 10 and 1 mM, respectively) of CuCl₂ according tothe method of the invention. Deposits can be clearly seen at the twohigher concentrations (the titania is not seen in the SEM images due toits insulating nature). EDX analysis confirmed that the deposits aremade of copper and the area between the deposits contains titania.Moreover, it is evident that the concentration of the Cu²⁺ stronglyaffects the morphology and grain size of the deposited copper. As theconcentration of Cu²⁺ in the solution increases, the average size of thegrains increases and their number per area decreases.

Since the electrochemical co-deposition is controlled by twosimultaneous processes, i.e., the reduction of Cu²⁺ and the depositionof titania, any parameter that controls the kinetics of each of theseprocesses, is likely to affect the morphology of the deposits. Indeed,lowering the applied potential to ±1.0 V decreases the kinetics oftitania deposition, while maintaining the reduction of copper underdiffusion-controlled conditions, such that a denser layer of copper(FIG. 2A, as compared with FIG. 1A) results. Likewise, when Ti(OPr)₄ wasreplaced by tetramethoxysilane, significantly larger aggregates ofcopper were obtained (FIG. 2B, as compared with FIG. 1A), reflecting theslower polycondensation of the silicon monomer.

The morphology of the deposited films can be clearly seen in FIGS. 3A-Bthat show part of a Cu/TiO₂ film which was peeled off the surface. TheCu/TiO₂ film is an electrochemically co-deposited film according to theinvention. From the cross-section shown in FIG. 3B the thickness of thelayer can be estimated at 160 nm.

The thickness of the film prepared according to the invention,independent of the surfaces used, can be varied not only by varying thedeposition time but also by varying the potential. Typically, films ofvarious thicknesses ranging from 1 nanometer to 100 micrometer have beenprepared.

Example 2 Electrodeposition of a Composite ContainingPhenyltrimethoxysilane (PhTMOS) and Polyethylene Glycol (20 kDa)

The composite was first prepared by adding 2.5 ml of 0.1M HCl to 1 ml ofPhTMOS, and then the mixture was dissolved in 6.5 ml EtOH. The solsolution was stirred at 40° C. After 1.5 h PEG 20,000 was added to themixture (in a 1:1 ratio to PhTMOS) and the stirring was continued untilit completely dissolved.

Without wishing to be bound by theory, it is understood that theinteraction between the sol-gel precursors and, e.g., the PEG added isone of covalent, electrostatic, hydrophobic-hydrophilic and hydrogenbonding. This interaction allows successful co-deposition of the twocomponents onto the surface.

The electrodeposition was carried out in a standard three-electrodecell. A potential of between (−1.7) V to (+2.6) V vs. Ag/AgBr wasapplied to the surface, e.g., ITO to be coated which was inserted intothe cell containing the solution for 1-10 min. FIG. 4A shows a barestainless steel surface and FIG. 4B shows a stainless steel surfacecoated with a two-phase film of sol-gel and PEG 20,000. As aggregates ofPEG 20,000 are not visual to the naked eye, the film is consideredhomogenous.

Example 3 Electrodeposition of a Composite ComprisingAminopropyltriethoxy Silane (APTEOS) or Phenyltrimethoxysilane (PhTMOS)and F127 Pluronic

The composite was prepared by adding 2.5 ml of 0.1M HCl to 1 ml ofAPTEOS, and then the mixture was dissolved in 6.5 ml EtOH. The solsolution was stirred at 25° C. at least 0.5 h prior before F127 pluronic(a block copolymer based on ethylene oxide and propylene oxide) wasadded to the mixture at a concentration of 5-10% of the silaneconcentration, and stirring was continued until complete dissolution.

The electrodeposition was conducted as detailed above on a stainlesssteel surface, and an exemplary films obtained are shown in FIGS. 5A and5B. As may be noted from the images, the two films contain aggregates ofpluronic which are of different sizes, shapes and distribution. Each ofthe aggregates contains a plurality of nanosize aggregates of pluronicembedded in the sol-gel polymer. These aggregates and nano-aggregatesare characteristic of two-phase films of APTEOS and pluronic.Homogenoues films of APTEOS and pluronic were also obtained.

Images shown in FIGS. 6A and 6B are of films of PhTMOS (FIG. 6A) and ofa composite of PhTMOS and pluonic (FIG. 6B). The images demonstrate thatat even at a much higher resolution of 30,000×, the film is homogenouswith no indication of polymer aggregates as demonstrated above. Further,one may note that the presence of the polymer in the film does notimpose any morphological change on the sol-gel coating. Both the sol-gelfilm alone (FIG. 6A) and the two-phase film of sol-gel and pluronic(FIG. 6B) exhibit identical morphology on the micro scale.

The heterogeneity of some PhTMOS films is exhibited in FIGS. 7A and 7B.These SEM images of a stent coated with a PhTMOS and pluronic show thevisible two phases, so called two-phase structure of the film.

It should be noted that the homogeneity or lack thereof of the film doesnot influence its short-term or long-term stability. Both homogenous andheterogeneous films fall within the scope of the present invention.

FIG. 8A shows a cross section of a coating formed upon adding onto atetramethoxysilane (TMOS) solution nanoparticles made of silica in whicha fluorescent dye was incorporated. From the cross section shown it isevident that the film is a dense phase embedded with nanoparticles. FIG.8B is a fluorescent optical micrograph indicating that the fluorescenceof the dye is kept upon electrochemical co-deposition.

Deposition of composites comprising conducting polymers, such aspolypyrrole, has also been accomplished. Typically, conducting polymersare made by the electropolymerization of monomers such as and not beinglimiting to pyrrole, aniline and thiophene or their derivatives, atpositive potentials. Since the electrodeposition of sol-gel can bedriven by either acidic or basic pH, the polymerization of such monomersindependently of the sol-gel process was also achieved (byelectrodeposition of a sol-gel monomer such as teteramethoxysilane andpyrrole) by applying positive potentials. The positive potentialdecreases the pH at the electrode surface and at the same time oxidizesthe pyrrole to form polypyrrole. The potential affects the ratio betweenthe electropolymerization of monomers of the conducting polymer andelectrodeposition of the sol-gel as can be seen in FIGS. 9-11.

In a typical experiment, a standard three-electrode cell was used. Apositive potential vs. Ag/AgBr was applied to a surface such asindium-tin oxide (ITO) for 1-10 min, while stirring the depositionsolution which contained 0.1 M pyrrole, 0.1 M sodium p-toluensulfonate(TsONa), tetraethoxysilane (TEOS), ethanol, HCl andN,N-dimethylformamide (for crack prevention). The ITO samples werepulled out of the deposition solution at a rate of 50 μm·sec⁻¹. The tworeactions shown below occurred simultaneously in the polypyrrole-silicasol-gel densification process to result in the polypyrrole-silicacomposite film.

FIGS. 9A-9D show SEM images of films that were electrodeposited afterapplying different positive potentials. It is evident that the appliedpotential strongly affected the morphology of the deposited films.

The effect of the potential may be observed further in FIG. 10A whichprovides a photograph of indium tin oxide substrates which were coatedwith a composite based on sol-gel and pyrrole. With different potentialsbeing applied, different film thicknesses were obtained. FIG. 10B showsa SEM image of the film that is formed at a potential of 2.3V. In thiscase, the conducting polymer is the continuous phase and the sol-gel arethe embedded particles. The ratio between the monomer of the conductingpolymer and that of the sol-gel dictates whether the two polymers willform two distinct phases, such as seen in FIG. 10B, or form a continuousone phase.

EDX analysis of the films formed according to the invention confirmedthe presence of silica and polypyrrole. It can be seen from FIGS.11A-11D that as the applied potential is more negative, the atomicpercent of nitrogen (from the polypyrrole) increases while the silicon(from the silica) decreases.

FIG. 12 demonstrates the absorbance measurements of the electrodepositedfilms, polypyrrole/SiO₂ at different applied potential.

In order to examine the influence of the deposition time, positivepotential was applied for different times. As FIG. 13 demonstrates, thelonger the deposition time was, the thicker the film was.

In order to examine the effect of the sol-gel monomer on theelectrodeposited films, different monomers were added to the depositionsolution, while the other parameters were kept same. FIGS. 14A-14B showSEM images of two-phase films of phenyltrimethoxysilane (PhTMOS) andpyrrole.

1-53. (canceled)
 54. A method for co-depositing on a conductive surfacea film of sol-gel and at least one additive, the method comprisinginducing an electrochemical reaction on the conductive surface in thepresence of a composite of at least one sol-gel precursor and at leastone additive, thereby obtaining a conductive surface coated with a film,the at least one additive being in the film in an amount greater than 1ppm.
 55. The method according to claim 54, comprising: (i) providing aconductive surface; (ii) providing a composite of at least one sol-gelprecursor and at least one additive in a solution; (iii) contacting thesurface with the solution comprising the composite; and (iv) applying avoltage to the surface in contact with the composite, thereby inducingformation of a sol-gel film on the surface.
 56. The method according toclaim 54, comprising: (i) providing a conductive surface; (ii) providinga composite of at least one sol-gel precursor and at least one additivein a solution; (iii) immersing said surface in a solution comprisingsaid composite, alcohol, water and at least one inert salt; (iv)applying a voltage to said surface being immersed in the solution,thereby inducing formation of a sol-gel film on said surface.
 57. Themethod according to claim 54, wherein the at least one sol-gel precursoris at least one monomer capable of undergoing electrochemicalpolymerization.
 58. The method according to claim 57, wherein themonomer is selected from the group consisting of a metal alkoxidemonomer, a transition metal alkoxide monomer, a silicon alkoxidemonomer, a metal ester monomer, a transition metal ester monomer, asilicon ester monomer, a monomer of the formula (RO)_(n)M(R′)_(4-n), apartially hydrolyzed and/or partially condensed polymer of each of saidmonomers, and mixtures thereof, wherein in the formula(RO)_(n)M(R′)_(4-n): M is selected from a silicon atom, a metallic orsemimetallic element, R is an organic moiety selected from C₁-C₃-alkyl,R′ is an organic moiety selected from C₁-C₁₀-alkyl, C₂-C₈-alkenyl,C₂-C₈-alkynyl, C₆-C₁₀-aryl and C₄-C₁₀-heteroaryl, optionally substitutedby at least one group selected from C₁-C₈-alkyl, C₂-C₈-alkenyl,C₂-C₈-alkynyl, C₆-C₁₀-aryl, C₄-C₁₀-heteroaryl, halide, amine (primary,secondary, tertiary or quaternary), hydroxyl, thiol, and nitro, and n isan integer from 1 to
 4. 59. The method according to claim 58, whereinthe monomers are selected from the group consisting of metal alkoxidemonomers and silicon alkoxide monomers.
 60. The method according toclaim 59, wherein the silicon alkoxide monomer is of the formula(RO)_(n)Si(R′)_(4-n), wherein R is an organic moiety selected fromC₁-C₃-alkyl, R′ is an organic moiety selected from C₁-C₁₀-alkyl orC₆-C₁₂-aryl, optionally substituted by at least one amine or thiolgroup, and n is an integer from 1 to 4, or a partially hydrolyzed and apartially condensed polymer thereof, or a mixture thereof.
 61. Themethod according to claim 58, wherein M is a metal atom or a transitionmetal atom selected from the group consisting of silicon, zirconium,aluminum, titanium, iron, tungsten, vanadium and mixtures thereof. 62.The method according to claim 54, wherein the at least one additive isinert to the sol-gel polymerization process.
 63. The method according toclaim 62, wherein the at least one additive is capable of undergoingreduction and/or polymerization under the electrochemical conditionsemployed.
 64. The method according to claim 62, wherein said at leastone additive is selected from the group consisting of reinforcingelements, metals, metal salts, fillers, polymers, monomers, prepolymers,nanoparticles, encapsulated materials, and composite matrix binders. 65.The method according to claim 64, wherein said at least one additive isin the form of a plurality of micro- or nanoparticles.
 66. The methodaccording to claim 54, comprising: (i) providing a conductive surface;(ii) immersing said surface in a solution comprising sol-gel precursors,at least one alcohol, water and at least one inert salt; (iii) inducingan electrochemical reaction on the conductive surface by applyingvoltage to the surface being immersed the solution; and (iv) treatingthe solution with at least one metal salt; thereby inducing theformation of a hybrid film of sol-gel and metal on the surface.
 67. Themethod according to claim 66, wherein the surface is a surface of amedical implant selected from the group consisting of a stent, anartificial heart valve, a cerebrospinal fluid shunt, a pacemakerelectrode, an axius coronary shunt, an endocardial lead, an orthopedicdevice, and a vessel occlusion device.
 68. A surface coated with a filmof sol-gel and at least one additive electrodeposited according to themethod of claim
 54. 69. The method according to claim 58, wherein R isan unsubstituted organic moiety selected from C₁-C₃-alkyl.